The invention relates to a multi-stage oil pumping system for an oil supply system of a motor vehicle including at least two oil pumps arranged axially adjacent one another.
In modern motor vehicles, the oil supply systems generally need several oil pumps or, respectively, oil pumping stages in which several pumps of the same type or different types of pumps are combined for supplying lubricating oil to various motor components.
DE 195 02 235 A1, for example, discloses an oil supply for a motor vehicle with a two-stage oil pumping system, wherein, in addition to a controllable pump, a constant volume pump is provided and both pumps are driven by a common drive shaft, the pumping direction of the controllable pump being changeable. This known two-stage oil pumping system is unusable for engines of different size because of its pumping characteristics.
The various oil pumps of a multi-stage oil pumping systems are often arranged serially, that is, one after the other or they are arranged in different areas of the engine compartment. With the serial arrangement, however, it is a disadvantage that a relatively long installation space is required. With the arrangement of the different pumps in different areas of the engine compartment on the other hand, the drive arrangement is complicated and the arrangement of the oil lines may also become quite complicated.
With spur gear pumps, it is furthermore possible, to drive in a single plane, two driven gears by a single drive gear. Such a two-stage spur gear pump system is for example disclosed in DE 101 40 066 A1.
Finally, DE 39 16 528 A1 discloses a multistage gear pump system wherein several axially adjacent gear stages are integrated into a housing. In a preferred arrangement, the several gear stages comprise three suction stages and one pressure stage which are all coupled to a shaft and driven by a common drive. This known multi-stage oil pumping system requires only a limited installation space and can be adapted to various internal combustion engine applications.
Based on the state of the art as described above it is the object of the present invention to provide a multi-stage oil pumping system for an oil supply system of a motor vehicle which ensures a high flexibility with regard to the operation of the pump and a high reliability and which additionally requires only a relatively small installation space.